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Abstract
ABSTRACTThe purpose of this study is to develop and extend our understanding of dementia care-giving by introducing a typology of informal care-giving across four different diseases. Care-giving factors were examined with respect to specific dementia presentation in mild cognitive impairment, Alzheimer's disease, dementia with Lewy bodies and Parkinson's disease-associated dementia. Informal care-giving literature in the four diseases was systematically searched to identify specific disease symptoms and resultant care-giving strains and outcomes. Key concepts were extracted and grouped thematically. The first classification, ‘role-shift’, reflects care-giving where cognitive deterioration results in changing roles, uncertainty and relational deprivation among married partners. The second classification, ‘consumed by care-giving’, refers to those caring for persons with dementia-motor decline that greatly increases worry and isolation. Finally, in the ‘service use’ classification, formal support is needed to help care-givers cope with daily responsibilities and behaviour changes. In each case, the dementia presentation uniquely impacts care-giver strains. A major conclusion is that the same support to all care-givers under the umbrella term ‘dementia’ is unwarranted; the development of targeted support is required.
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Bonanni L, Perfetti B, Bifolchetti S, Taylor JP, Franciotti R, Parnetti L, Thomas A, Onofrj M. Quantitative electroencephalogram utility in predicting conversion of mild cognitive impairment to dementia with Lewy bodies. Neurobiol Aging 2014; 36:434-45. [PMID: 25129239 PMCID: PMC4270449 DOI: 10.1016/j.neurobiolaging.2014.07.009] [Citation(s) in RCA: 85] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 06/19/2014] [Accepted: 07/08/2014] [Indexed: 11/25/2022]
Abstract
Mild cognitive impairment (MCI) as a precursor of dementia with Lewy bodies (DLB) is the focus of recent research, trying to explore the early mechanisms and possible biomarkers of DLB. Quantitative electroencephalogram (QEEG) methods are able to differentiate early DLB from Alzheimer's disease (AD). The aim of the present study was to assess whether QEEG abnormalities, characterized by dominant frequency <8 Hz and dominant frequency variability >1.5 Hz, typical of early DLB, are already present at the stage of MCI and to evaluate whether EEG abnormalities can predict the development of DLB. Forty-seven MCI subjects were followed for 3 years. EEG recordings were obtained at admission and at the end of the study. At the end of follow-up, 20 subjects had developed probable DLB (MCI-DLB), 14 had probable AD (MCI-AD), 8 did not convert to dementia, 5 developed a non-AD/DLB dementia. One hundred percent of MCI-DLB showed EEG abnormalities at admission. Ninety three percent of MCI-AD maintained a normal EEG throughout the study. QEEG may represent a powerful tool to predict the progression from MCI to DLB with a sensitivity and specificity close to 100%. We studied in mild cognitive impairment (MCI) subjects the predictive value of electroencephalogram (EEG) alterations for the development of dementia with Lewy bodies (DLB). One hundred percent of MCI subjects converted to DLB already had EEG alterations typical of DLB (dominant frequency <8 Hz and dominant frequency variability ≥1.5 Hz) at admission to the study. Quantitative EEG may represent a powerful tool to predict the progression from MCI to DLB.
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Affiliation(s)
- Laura Bonanni
- Department of Neuroscience and Imaging, G. d'Annunzio University, Chieti, Italy; Aging Research Centre, Ce.S.I., G. d'Annunzio University Foundation, Chieti, Italy.
| | - Bernardo Perfetti
- Department of Neuroscience and Imaging, G. d'Annunzio University, Chieti, Italy; Aging Research Centre, Ce.S.I., G. d'Annunzio University Foundation, Chieti, Italy
| | - Stefania Bifolchetti
- Department of Neuroscience and Imaging, G. d'Annunzio University, Chieti, Italy; Aging Research Centre, Ce.S.I., G. d'Annunzio University Foundation, Chieti, Italy
| | - John-Paul Taylor
- Institute for Ageing and Health, Newcastle University, Campus for Ageing and Vitality, Newcastle upon Tyne, UK
| | - Raffaella Franciotti
- Department of Neuroscience and Imaging, G. d'Annunzio University, Chieti, Italy; Institute for Advanced Biomedical Technologies (ITAB), G. d'Annunzio University Foundation, Chieti, Italy
| | - Lucilla Parnetti
- Center for Memory Disturbances and Alzheimer's Center, Section of Neurology, University of Perugia, Perugia, Italy
| | - Astrid Thomas
- Department of Neuroscience and Imaging, G. d'Annunzio University, Chieti, Italy; Aging Research Centre, Ce.S.I., G. d'Annunzio University Foundation, Chieti, Italy
| | - Marco Onofrj
- Department of Neuroscience and Imaging, G. d'Annunzio University, Chieti, Italy; Aging Research Centre, Ce.S.I., G. d'Annunzio University Foundation, Chieti, Italy
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Zweig YR, Galvin JE. Lewy body dementia: the impact on patients and caregivers. ALZHEIMERS RESEARCH & THERAPY 2014; 6:21. [PMID: 25031635 PMCID: PMC4054937 DOI: 10.1186/alzrt251] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Lewy body dementia (LBD) is the second most common neurodegenerative dementia in older adults, yet there remains a delay in diagnosis that limits healthcare providers’ ability to maximize therapeutic outcomes and enhance patient and caregiver quality of life. The impact of LBD on patients includes limiting the potential exposure to medications that may cause adverse outcomes, and addressing how the disease manifestations, such as autonomic features and behavior, affect quality of life. LBD impact on caregivers has been discussed to a greater degree in the literature, and there is clear evidence of caregiver burden and grief associated with disease manifestations. Other common caregiving concerns, such as access to care, prevention of hospitalization, managing behavior, and reviewing prognosis and nursing home placement, are important to comprehensively address the needs of patients with LBD and their caregivers.
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Affiliation(s)
- Yael R Zweig
- Departments of Neurology, Psychiatry and Population Health, Alzheimer Disease Center, New York University School of Medicine, New York, NY 10016, USA
| | - James E Galvin
- Departments of Neurology, Psychiatry and Population Health, Alzheimer Disease Center, New York University School of Medicine, New York, NY 10016, USA
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Utility of neuropsychiatric tools in the differential diagnosis of dementia with Lewy bodies and Alzheimer's disease: quantitative and qualitative findings. Int Psychogeriatr 2014; 26:453-61. [PMID: 24284139 DOI: 10.1017/s1041610213002068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Discerning dementia with Lewy bodies (DLB) from Alzheimer's disease (AD) is one of the most common and challenging differential diagnoses at the memory clinic. Although the neuropsychiatric manifestations have been widely reported as one of the main key points in the differential diagnosis between these two diseases, to date no neuropsychiatric questionnaire has been specifically devised for this purpose. METHODS We administered the Neuropsychiatric Inventory (NPI) and the Columbia University Scale for Psychopathology in Alzheimer's Disease (CUSPAD) to a memory clinic sample of 80 patients with probable DLB and 85 age- and severity-matched patients with probable AD. Diagnosis of probable DLB was supported with a positive dopamine transporter SPECT scan. We examined the usefulness of these two neuropsychiatric tools designed for AD in the differential diagnosis between DLB and AD. We also investigated the correlations between psychotic symptoms and measures of cognitive and functional decline. RESULTS Auditory hallucinations were very specific of DLB and were usually preceded by visual hallucinations. Misinterpretation of real visual stimuli (illusions) was more frequent in DLB. Delusions were both quantitatively and qualitatively different between DLB and AD: delusional misidentifications were significantly more characteristic of DLB, while paranoid delusions did not show specificity for DLB. CONCLUSIONS Neuropsychiatric tools are useful to discriminate DLB from AD. Hallucinations and delusions are not only more frequent in DLB than in AD but also have distinct qualitative characteristics and patterns of progression that can help clinicians to make a more accurate differential diagnosis.
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Rolma G, Jelcic N, Gnoato F, Cecchin D, Cagnin A. Combined duloxetine and benzodiazepine-induced visual hallucinations in prodromal dementia with Lewy bodies. Gen Hosp Psychiatry 2013; 35:678.e7-9. [PMID: 23523020 DOI: 10.1016/j.genhosppsych.2013.02.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Revised: 02/12/2013] [Accepted: 02/12/2013] [Indexed: 11/19/2022]
Abstract
OBJECTIVE We describe a patient with prodromal dementia with Lewy bodies (DLB) presenting with drug-induced visual hallucinations (VHs). CASE REPORT A 78-year-old woman complained of daytime recurrent VHs characterized by seeing her face and arms covered in fur and viewing moustaches on her daughter's face. VHs started a few days after the beginning of a combination therapy with duloxetine and lorazepam and ceased within 24 h after their discontinuation. Nonamnestic mild cognitive impairment with profound visual perception deficits and very mild extrapyramidal signs, with abnormal brain DaTscan single photon emission tomography, were present. Three years later, cognitive and neurological follow-up assessments supported the diagnosis of DLB. CONCLUSION Perturbation of cerebral serotonergic tone induced by duloxetine, associated with reduced attentional control due to benzodiazepine use, may be the physiopathological substrate of transient VHs in prodromal DLB.
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Affiliation(s)
- Giacomo Rolma
- Department of Neurosciences: Sciences NPSRR, University of Padova, Padova, Italy
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56
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Toledo JB, Cairns NJ, Da X, Chen K, Carter D, Fleisher A, Householder E, Ayutyanont N, Roontiva A, Bauer RJ, Eisen P, Shaw LM, Davatzikos C, Weiner MW, Reiman EM, Morris JC, Trojanowski JQ. Clinical and multimodal biomarker correlates of ADNI neuropathological findings. Acta Neuropathol Commun 2013; 1:65. [PMID: 24252435 PMCID: PMC3893373 DOI: 10.1186/2051-5960-1-65] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 09/23/2013] [Indexed: 12/11/2022] Open
Abstract
Background Autopsy series commonly report a high percentage of coincident pathologies in demented patients, including patients with a clinical diagnosis of dementia of the Alzheimer type (DAT). However many clinical and biomarker studies report cases with a single neurodegenerative disease. We examined multimodal biomarker correlates of the consecutive series of the first 22 Alzheimer’s Disease Neuroimaging Initiative autopsies. Clinical data, neuropsychological measures, cerebrospinal fluid Aβ, total and phosphorylated tau and α-synuclein and MRI and FDG-PET scans. Results Clinical diagnosis was either probable DAT or Alzheimer’s disease (AD)-type mild cognitive impairment (MCI) at last evaluation prior to death. All patients had a pathological diagnosis of AD, but only four had pure AD. A coincident pathological diagnosis of dementia with Lewy bodies (DLB), medial temporal lobe pathology (TDP-43 proteinopathy, argyrophilic grain disease and hippocampal sclerosis), referred to collectively here as MTL, and vascular pathology were present in 45.5%, 40.0% and 22.7% of these patients, respectively. Hallucinations were a strong predictor of coincident DLB (100% specificity) and a more severe dysexecutive profile was also a useful predictor of coincident DLB (80.0% sensitivity and 83.3% specificity). Occipital FDG-PET hypometabolism accurately classified coincident DLB (80% sensitivity and 100% specificity). Subjects with coincident MTL showed lower hippocampal volume. Conclusions Biomarkers can be used to independently predict coincident AD and DLB pathology, a common finding in amnestic MCI and DAT patients. Cohorts with comprehensive neuropathological assessments and multimodal biomarkers are needed to characterize independent predictors for the different neuropathological substrates of cognitive impairment.
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Abstract
Dementia with Lewy bodies (DLB) is the second most common form of dementia after Alzheimer disease (AD). DLB is characterized pathologically by Lewy body and Lewy neuritic pathology, often with variable levels of Alzheimer-type pathology. Core clinical features include fluctuating cognition, visual hallucinations, and parkinsonism resulting in greater impairments of quality of life, more caregiver burden, and higher health-related costs compared with AD. These issues, together with a high sensitivity to adverse events with treatment with antipsychotic agents, make the need for an early and accurate diagnosis of DLB essential. Unfortunately, current consensus criteria are highly specific but lack sufficient sensitivity. Use of composite risk scores may improve accuracy of clinical diagnosis. Imaging findings, particularly targeting dopaminergic systems have shown promise as potential markers to differentiate DLB from AD. A combination of non-pharmacologic treatments and pharmacotherapy interventions may maximize cognitive function and overall quality of life in DLB patients.
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Östling S, Bäckman K, Waern M, Marlow T, Braam AW, Fichter M, Lawlor BA, Lobos A, Reischies FM, Copeland JRM, Skoog I. Paranoid symptoms and hallucinations among the older people in Western Europe. Int J Geriatr Psychiatry 2013; 28:573-9. [PMID: 22911450 DOI: 10.1002/gps.3861] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 06/25/2012] [Indexed: 11/11/2022]
Abstract
OBJECTIVE It is not clear whether the prevalence of psychosis increases with age. We studied the age-specific prevalence of psychotic symptoms in older people in Western Europe. METHODS Older people without dementia (age 65-104 years, N = 8762) from the western part of Europe in the EURODEP concerted action took part in psychiatric examinations. RESULTS In total, 2.4% of the men and 2.9% of the women had psychotic symptoms. Using a multilevel logistic regression model that included gender and age as a continuous variable, we found that a 5-year increase in age increased the prevalence of psychotic symptoms (odds ratio 1.2 95% confidence interval 1.06-1.3, p = 0.001). A second multilevel regression model showed that wishing to be dead, depressed mood, functional disability, not being married and cognitive impairment measured with Mini mental state examination were all associated with psychotic symptoms whereas gender was not. CONCLUSION The prevalence of psychotic symptoms in non-demented older people increases with age, and these symptoms are associated with other psychopathology, social isolation and problems with daily living.
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Affiliation(s)
- Svante Östling
- Institute of Neuroscience and Physiology, Psychiatry Section, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
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Scarr E, Gibbons AS, Neo J, Udawela M, Dean B. Cholinergic connectivity: it's implications for psychiatric disorders. Front Cell Neurosci 2013; 7:55. [PMID: 23653591 PMCID: PMC3642390 DOI: 10.3389/fncel.2013.00055] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 04/12/2013] [Indexed: 01/01/2023] Open
Abstract
Acetylcholine has been implicated in both the pathophysiology and treatment of a number of psychiatric disorders, with most of the data related to its role and therapeutic potential focusing on schizophrenia. However, there is little thought given to the consequences of the documented changes in the cholinergic system and how they may affect the functioning of the brain. This review looks at the cholinergic system and its interactions with the intrinsic neurotransmitters glutamate and gamma-amino butyric acid as well as those with the projection neurotransmitters most implicated in the pathophysiologies of psychiatric disorders; dopamine and serotonin. In addition, with the recent focus on the role of factors normally associated with inflammation in the pathophysiologies of psychiatric disorders, links between the cholinergic system and these factors will also be examined. These interfaces are put into context, primarily for schizophrenia, by looking at the changes in each of these systems in the disorder and exploring, theoretically, whether the changes are interconnected with those seen in the cholinergic system. Thus, this review will provide a comprehensive overview of the connectivity between the cholinergic system and some of the major areas of research into the pathophysiologies of psychiatric disorders, resulting in a critical appraisal of the potential outcomes of a dysregulated central cholinergic system.
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Affiliation(s)
- Elizabeth Scarr
- Department of Psychiatry, The University of MelbourneParkville, VIC, Australia
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental HealthParkville, VIC, Australia
| | - Andrew S. Gibbons
- Department of Psychiatry, The University of MelbourneParkville, VIC, Australia
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental HealthParkville, VIC, Australia
| | - Jaclyn Neo
- Department of Psychiatry, The University of MelbourneParkville, VIC, Australia
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental HealthParkville, VIC, Australia
| | - Madhara Udawela
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental HealthParkville, VIC, Australia
- Centre for Neuroscience, The University of MelbourneParkville, VIC, Australia
| | - Brian Dean
- Department of Psychiatry, The University of MelbourneParkville, VIC, Australia
- Molecular Psychiatry Laboratories, Florey Institute of Neuroscience and Mental HealthParkville, VIC, Australia
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Abstract
BACKGROUND Dementia with Lewy bodies (DLB) is the second most common type of neurodegenerative dementia. It is frequently difficult to differentiate DLB from Alzheimer's disease (AD) and other types of dementia. This study examined the usefulness of monitoring sleep talking for the diagnosis of DLB. METHODS A total of 317 patients with dementia were selected from a consecutive series at the Dementia Clinic of Kumamoto University Hospital. Diagnostic categories consisted of probable DLB (n = 55), probable AD (n = 191), frontotemporal lobar degeneration (FTLD) (n = 16), vascular dementia (VaD) (n = 18), and other/unspecified dementia (n = 37). We evaluated sleep talking in all dementia patients and normal elderly subjects (n = 32) using an originally designed sleep talking questionnaire. RESULTS Sleep talking occurred most frequently in the DLB group (61.8%), followed by the VaD group (33.3%), other/unspecified dementia group (27.0%), AD group (18.8%), FTLD group (12.5%), and normal elderly subjects group (6.3%). The prevalence of sleep talking in the DLB group was significantly higher than in other groups, except in the VaD group. The sleep talking yielded high specificity (81.2%) and some sensitivity (61.8%) for the differential diagnosis of DLB from AD. Furthermore, loud sleep talking may improve the specificity (96.9%). For the differentiation of DLB from all other dementia types, the specificity of sleep talking and loud sleep talking was also high (79.4% and 95.8% respectively). CONCLUSIONS Assessing sleep talking, especially the volume of sleep talking, may be useful in the clinical discrimination of DLB from not only AD but also from all other types of dementia.
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Huang Y, Halliday G. Can we clinically diagnose dementia with Lewy bodies yet? Transl Neurodegener 2013; 2:4. [PMID: 23398715 PMCID: PMC3575256 DOI: 10.1186/2047-9158-2-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Accepted: 02/06/2013] [Indexed: 12/20/2022] Open
Abstract
Dementia with Lewy Bodies (DLB) was initially identified and confirmed primarily by pathology, but is soon to be incorporated into the Diagnostic and Statistical Manual criteria as a clinical disease entity. Despite these advances over more than 20 years, current data suggest that the sensitivity of accurate clinical diagnosis of DLB is still very low, although there is mounting evidence that supportive features may increase diagnostic accuracy. Although DLB remains easy to identify pathologically with different cellular pathologies differentiating it from other dementia syndromes, pathological identification using only Lewy body pathology has been shown to be inaccurate due to overlap with patients without dementia symptoms. A number of studies now suggest that a combination of cellular pathologies, which include α-synuclein and β-amyloid deposition as well as dopamine denervation, assist with differentiating this dementia syndrome from others. The clinical and pathological overlap with the tauopathy of Alzheimer's disease still remains to be clarified. To determine more robust and independent clinicopathological correlates from Alzheimer's disease, longitudinal prospective studies, using specific clinical batteries on dementia patients reaching the proposed criteria for DLB, with post-mortem assessment of the multiple pathologies associated with dementia, are required. Identifying genetic causes for DLB is another approach to investigate the pathogenesis of DLB. However this approach has been hindered to date by difficulties with identifying DLB clinically. The use of novel techniques is likely to advance knowledge on the pathogenesis of DLB and assist with redefining clinical and pathologic diagnostic criteria. To achieve the goal of more accurate clinical diagnosis of DLB, breakthroughs are necessary on the pathogenesis of DLB.
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Affiliation(s)
- Yue Huang
- Neuroscience Research Australia, The University of New South Wales, Sydney, NSW, 2031, Australia.
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Bjoerke-Bertheussen J, Ehrt U, Rongve A, Ballard C, Aarsland D. Neuropsychiatric symptoms in mild dementia with lewy bodies and Alzheimer's disease. Dement Geriatr Cogn Disord 2013; 34:1-6. [PMID: 22854420 DOI: 10.1159/000339590] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/14/2012] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS To compare neuropsychiatric symptoms in patients with Alzheimer's disease (AD) and dementia with Lewy bodies(DLB). METHODS Neuropsychiatric symptoms and caregiver distress were assessed using the Neuropsychiatric Inventory (NPI) in mild DLB (n = 57) and AD (n = 126), and compared across the two groups using non-parametric tests. RESULTS The DLB patients had a higher NPI totalscore (median 24 vs. 11.5, p < 0.005), more numerous symptoms (median 5 vs. 4, p = 0.001) and more clinically significant symptoms (3 vs. 1, p = 0.001). They also had higher item hallucinations (6 vs. 2, p < 0.005) and apathy (7 vs. 5, p = 0.002) subscores. Caregivers scored higher on the NPI total caregiver distress scale (12.5 vs. 6, p = 0.003). CONCLUSIONS In mild dementia, DLB patients have more neuropsychiatric symptoms and more associated caregiver distress compared with AD.
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Affiliation(s)
- J Bjoerke-Bertheussen
- Department of Psychiatry, Centre for Age-Related Medicine, Stavanger University Hospital, Stavanger, Norway
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Agonist high- and low-affinity states of dopamine D₂ receptors: methods of detection and clinical implications. Naunyn Schmiedebergs Arch Pharmacol 2012; 386:135-54. [PMID: 23224422 DOI: 10.1007/s00210-012-0817-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 11/22/2012] [Indexed: 01/10/2023]
Abstract
Dopamine D(2) receptors, similar to other G-protein-coupled receptors, exist in a high- and low-affinity state for agonists. Based upon a review of the methods for detecting D(2) receptor agonist high-affinity states, we discuss alterations of such states in animal models of disease and the implications of such alterations for their labelling with positron emission tomography (PET) and single-photon emission computed tomography (SPECT) tracers. The classic approach of detecting agonist high-affinity states compares agonist competition for antagonist radioligands, in most cases using [(3)H]-spiperone as the radioligand; alternative approaches and radioligands have been proposed, but their claimed advantages have not been substantiated by other investigators. In view of the advantages and disadvantages of various techniques, we critically have reviewed reported findings on the detection of D(2) receptor agonist high-affinity states in a variety of animal models. These data are compared to the less numerous findings from human in vivo studies based on PET and SPECT tracers; they are interpreted in light of the finding that D(2) receptor agonist high-affinity states under control conditions may differ between rodent and human brain. The potential advantages of agonist ligands in studies of pathophysiology and as diagnostics are being discussed.
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